All Aquarium Calculators
Five free tools that do the maths for your tank — volume, stocking density, Walstad soil, nano planning, and bowl setup. No signup, no paywall, runs entirely in your browser.
Tank Size Calculator
Calculate your tank's exact water volume in gallons and litres. Supports rectangular, bowfront, and hexagonal shapes.
Most popularFish Stocking Calculator
How many fish can your tank safely hold? Uses bioload, surface area, and filtration — not the outdated inch-per-gallon rule.
EssentialNano Stocking Wizard
Get a curated stocking plan for tanks under 60 litres. Picks compatible species based on your tank size and experience level.
For small tanksWalstad Soil Calculator
Calculate exactly how much soil and cap material you need for a Walstad-method planted tank. No guessing, no waste.
Planted tanksWalstad Bowl Planner
Plan a self-sustaining Walstad bowl — soil, plants, stocking, and maintenance schedule tailored to your bowl size.
Low-techBristlenose Genetics Calculator
Predict offspring colours and fin types from bristlenose pleco breeding pairs. Covers albino, longfin, and super-red genetics.
For breedersWhich calculator do I need?
Just starting out? Run the Tank Size Calculator first to find your real water volume, then the Stocking Calculator to plan your fish list.
Setting up a planted tank? Use the Walstad Soil Calculator to get the right substrate depth, then read the Walstad Method Guide.
Small tank (under 60 L)? The Nano Stocking Wizard gives you ready-made stocking plans tuned for nano tanks.